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  • 1
    Publication Date: 2010-04-23
    Description: Vast world reserves of methane gas are underutilized as a feedstock for the production of liquid fuels and chemicals owing to the lack of economical and sustainable strategies for the selective oxidation of methane to methanol. Current processes to activate the strong C-H bond (104 kcal mol(-1)) in methane require high temperatures, are costly and inefficient, and produce waste. In nature, methanotrophic bacteria perform this reaction under ambient conditions using metalloenzymes called methane monooxygenases (MMOs). MMOs thus provide the optimal model for an efficient, environmentally sound catalyst. There are two types of MMO. Soluble MMO (sMMO) is expressed by several strains of methanotroph under copper-limited conditions and oxidizes methane with a well-characterized catalytic di-iron centre. Particulate MMO (pMMO) is an integral membrane metalloenzyme produced by all methanotrophs and is composed of three subunits, pmoA, pmoB and pmoC, arranged in a trimeric alpha(3)beta(3)gamma(3) complex. Despite 20 years of research and the availability of two crystal structures, the metal composition and location of the pMMO metal active site are not known. Here we show that pMMO activity is dependent on copper, not iron, and that the copper active site is located in the soluble domains of the pmoB subunit rather than within the membrane. Recombinant soluble fragments of pmoB (spmoB) bind copper and have propylene and methane oxidation activities. Disruption of each copper centre in spmoB by mutagenesis indicates that the active site is a dicopper centre. These findings help resolve the pMMO controversy and provide a promising new approach to developing environmentally friendly C-H oxidation catalysts.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2999467/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2999467/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Balasubramanian, Ramakrishnan -- Smith, Stephen M -- Rawat, Swati -- Yatsunyk, Liliya A -- Stemmler, Timothy L -- Rosenzweig, Amy C -- DK068139/DK/NIDDK NIH HHS/ -- GM070473/GM/NIGMS NIH HHS/ -- R01 DK068139/DK/NIDDK NIH HHS/ -- R01 DK068139-05/DK/NIDDK NIH HHS/ -- R01 GM070473/GM/NIGMS NIH HHS/ -- R01 GM070473-07/GM/NIGMS NIH HHS/ -- England -- Nature. 2010 May 6;465(7294):115-9. doi: 10.1038/nature08992. Epub 2010 Apr 21.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, Illinois 60208, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20410881" target="_blank"〉PubMed〈/a〉
    Keywords: Catalytic Domain ; Copper/*chemistry ; Methane/*metabolism ; Methanol/chemistry ; Methylococcus capsulatus/*enzymology ; Methylosinus trichosporium/enzymology ; *Models, Molecular ; Mutation ; Oxidation-Reduction ; Oxygenases/*chemistry/genetics/metabolism ; Protein Structure, Tertiary
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2013-02-09
    Description: HSP-100 protein machines, such as ClpB, play an essential role in reactivating protein aggregates that can otherwise be lethal to cells. Although the players involved are known, including the DnaK/DnaJ/GrpE chaperone system in bacteria, details of the molecular interactions are not well understood. Using methyl-transverse relaxation-optimized nuclear magnetic resonance spectroscopy, we present an atomic-resolution model for the ClpB-DnaK complex, which we verified by mutagenesis and functional assays. ClpB and GrpE compete for binding to the DnaK nucleotide binding domain, with GrpE binding inhibiting disaggregation. DnaK, in turn, plays a dual role in both disaggregation and subsequent refolding of polypeptide chains as they emerge from the aggregate. On the basis of a combined structural-biochemical analysis, we propose a model for the mechanism of protein aggregate reactivation by ClpB.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rosenzweig, Rina -- Moradi, Shoeib -- Zarrine-Afsar, Arash -- Glover, John R -- Kay, Lewis E -- Canadian Institutes of Health Research/Canada -- New York, N.Y. -- Science. 2013 Mar 1;339(6123):1080-3. doi: 10.1126/science.1233066. Epub 2013 Feb 7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada. rina.rosenzweig@utoronto.ca〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23393091" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphatases/*chemistry/genetics ; Adenosine Triphosphate/chemistry/metabolism ; Bacterial Proteins/chemistry ; Heat-Shock Proteins/*chemistry/genetics ; Hydrolysis ; *Models, Chemical ; Mutation ; Nuclear Magnetic Resonance, Biomolecular ; Protein Interaction Domains and Motifs ; Protein Interaction Maps ; Protein Multimerization ; *Protein Refolding ; Protein Structure, Tertiary ; Protein Transport ; Thermus thermophilus
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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